During a collision, rollover or other abrupt event, a vehicle can be subjected to abruptly changing forces from various different directions, and can be subjected to both positive and negative gravitational forces with rapid acceleration and deceleration. The forces travel throughout the vehicle body and can travel from the door panel to the door handle in what can be characterized as a ripple effect.
It is desirable that the vehicle doors remain closed during a severe vehicle event such as a collision or rollover. Some door latch mechanisms can operate unintentionally when subjected to high acceleration under varying positional orientations, or to the ripple effect of forces that can occur during a crash or other severe vehicle event. Accordingly, it is known to provide lockout mechanisms of various types to prevent the unintended operation of the door latch mechanism during a severe vehicle event. Counterweights positioned opposite to the pivot of the door handle can be effective against side impact forces; however, during a rollover or other such complex, multiple axis event the counterweight can become positioned so as to allow latch operation. Counterweight systems also tend to be bulky, requiring significant space. Further, counterweight systems operate effectively only to a limited acceleration as determined from the design of the system. If the acceleration during an event exceeds the designed limit, the counterweight system is not effective in preventing the door from opening.
Another known design, referred to as an inertia activated mechanism, locks out operation of the latch handle mechanism even as the forces change during a severe vehicle event. Inertia activated mechanisms have been effective against the complex, rapidly changing force patterns experienced in rollovers and other such events in that the inertia activated mechanism operates initially regardless of the direction applied force. Further, inertia activated mechanisms remain effective even under severe acceleration and are not limited by the magnitude of acceleration.
During some severe vehicle events, abruptly changing inertial forces can rapidly change from positive to negative gravitational force and can rapidly change direction. An inertia activated mechanism rapidly changing in orientation and position can momentarily pass through a position in which the mechanism can return to its standard position for door latch mechanism operation. While such positioning can be brief, it is desirable to delay the return of the inertia activated mechanism to its latch operational position so that unintended vehicle door opening does not occur if the mechanism momentarily passes through the original orientation.
Accordingly, there is a need for improved vehicle latch lockout mechanisms that maintain operational lockout of the latch mechanism even under severe, multi-access vehicle events such as vehicle crashes and rollovers.